The present invention relates to sewing machines with differential feed.
Sewing machines having differential feed are generally known for example from German Patent Specification 10 71 461 corresponding to U.S. Pat. No. 2,965,056. In sewing machines having differently adjusted feed stroke lengths of main and differential material feed dogs, there is a particular ratio between these two feed stroke lengths. If this ratio alters as a result of an increase in the feed stroke length of the differential feed dog, in the case of known sewing machines with differential feed, the length of the stitch in the material to be sewn will also increase. Such a result is disadvantageous. In order to maintain the same stitch length, it is necessary, given a change in the differential ratio, to make a time-consuming readjustment of the main feed.